1. Field of the Invention
The present invention relates to an optical switch device which is provided on an optical path of an optical waveguide and switches an advancing direction of an incident light to the optical waveguide.
2. Description of the Related Art
In recent years, an optical network is developed for transmitting mass information, and an optical switch as device for dividing a light is used for the optical network. A conventional optical switch switches a light between linear advancing and reflection in such a manner that a micromirror provided on an optical path of a light flux emitted from an optical fiber is supported by a movable plate and the movable plate is moved by applying a voltage so that the micromirror is retracted from the optical path. However, such an optical switch additionally requires a movable plate for moving a micromirror.
In addition, there has been conventionally suggested an optical switch in which a groove section which slantly crosses two crossing optical waveguides is provided, air bubbles are formed in a liquid filling the groove section and the air bubbles are heated by a microheater so as to be moved. According to this optical switch, since a refractive index of the filling liquid and a refractive index of the optical waveguides are set to be approximately equal with each other, when the liquid is provided onto the optical paths of the optical waveguides, a light advances straight, and when air bubbles are provided, a light is reflected so that the advancing direction is switched. However, since such an optical switch carries out heating, it requires a microheater and a heat radiating mechanism.
Besides the above-mentioned optical switches, there is an optical switch which uses a micropump having piezoelectric element or a magnetic force of a magnetic coil in order to drive a mirror or a filter provided on a crossed section of two optical waveguides. However, in a driving mechanism such as a micropump which utilizes a liquid, it is difficult to stop a filter on a predetermined position and its locating mechanism becomes complicated. Moreover, in the case where an electromagnetic force of a coil or the like is used, a driving force generating section including the coil for driving a filter becomes complicated and thus becomes large. Therefore, in those conventional optical switches, there arises a problem that their structure becomes complicated.
Further, in recent years, so-called wavelength multiplex communication is carried out. With this wavelength multiplex communication, different pieces of information are placed on lights (carrier waves) with different wavelengths and a plurality of carrier waves are superposed so that mass information can be transmitted by one optical fiber. However, according to the above-mentioned conventional optical switch, since the lights where wavelengths are multiplexed are reflected or transmitted uniformly, pieces of information placed on the carrier waves cannot be output separately. For this reason, since the pieces of information are branched by an additional branching filter or the like so as to be taken out, there arises a problem that an optical communication system having an optical switch becomes complicated.